1. Field of the Disclosure
The present invention relates generally to electrophotographic printers and more particularly to a shutter for a developer unit and a toner cartridge having engagement features to actuate the shutter.
2. Description of the Related Art
In order to reduce the premature replacement of components traditionally housed within a toner cartridge for an image forming device, toner cartridge manufacturers have begun to separate components having a longer life from those having a shorter life into separate replaceable units. Relatively longer life components such as a developer roll, a toner adder roll and a doctor blade are positioned in one replaceable unit (a “developer unit”). The image forming device's toner supply, which is consumed relatively quickly in comparison with the components housed in the developer unit, is provided in a reservoir in a separate replaceable unit in the form of a toner cartridge that mates with the developer unit. In this configuration, the number of components housed in the toner cartridge is reduced in comparison with traditional toner cartridges.
Image forming devices having a separate toner cartridge and developer unit are susceptible to leakage of toner between an outlet port of the toner cartridge and an inlet port of the developer unit. Toner leakage is most frequently experienced when the toner cartridge is separated from the developer unit and removed from the image forming device. When this occurs, handling, moving or shipping of the image forming device may cause toner to escape from the inlet port of the developer unit. Leaked toner may contaminate both internal and external surfaces of the image forming device resulting in not only uncleanliness but, in some cases, reliability issues or print defects. Accordingly, a developer unit having a shutter for ensuring that toner does not escape the developer unit when the toner cartridge is removed is desired.
Providing such a shutter presents several challenges. First, the developer unit must be precisely positioned relative to its corresponding photoconductive drum. Otherwise, print defects may occur such as “white gapping” where the developer roll momentarily separates from the photoconductive drum and fails to supply toner to the drum. Accordingly, the force balance on the developer unit must be tightly controlled. Second, the timing of the opening and closing of a shutter on the inlet port of the developer unit must be precise relative to the insertion or removal of the toner cartridge and the opening and closing of a corresponding shutter on the outlet port of the toner cartridge. Third, both the shutter on the outlet port of the toner cartridge and the shutter on the inlet port of the developer unit must open and close reliably upon cartridge insertion and removal over the life of the components and throughout a range of part tolerances and cartridge insertion paths.